Posted by Kent Staubus on August 25, 2007 at 4:42 PM
Nikon and Canon have both announced new midpriced cameras, 40D and D300. On other message boards I read posts such as, "Oh wow the new one is 12 mp now. I'm going to buy one!" My thinking is an increase of only 2 mp is no big deal at all. When I started to look closer at the specs I became suspicious. The Canon 30D has a sensor of 8.1 mp and pixel pitch is 6.4 microns. The 40D has a 10.1 mp sensor and pixel pitch is 5.7 microns. Nikon seems to be doing the same. The D200/D80 sensor is 10.2 mp and pixel pitch is 6.05 microns; the D300 sensor is 12.3 and pixel pitch is 5.5 microns.
Enough of the numbers. As a general rule, the bigger the pixel pitch (actual size of the pixel sensor) the lower the noise, and the better the high ISO/low light performance. So, are Canon & Nikon just playing games here? It looks like all they have done is pack a few more pixels onto their sensor by making them smaller. Isn't there a risk the image quality will actually be lower, especially in low light? One thing I can't figure in is Nikon's switch from CCD to CMOS. Not sure if one is better than another. The appearance is they are both trying to jam more but smaller pixels onto a sensor to impress the less sophisticated buyers. The processing did go up from 12 bit to 14 bit. Will that be enough to overcome the smaller pixel pitch? Maybe we'll have to wait until there are actual image samples.
Kent in SD
Posted by David Bostedo on August 25, 2007 at 4:58 PM
Kent - The thing you have to remember is that larger pixels make it easier to get good performance. That doesn't mean that given circuit changes, A/D changes, microlens changes, etc, that a sensor with smaller pixels can't outperform one with larger pixels. The key thing is that all else equal a larger pixel will outperform a smaller pixel - but in the case of a new sensor and processor, all else is not equal.
Now I don't know if this means that the new sensors will definitely be better. The jump from 8 to 10 MP is not very large, but if you're making prints it's that much less you have to enlarge for a given size print, which also helps with apparent quality.
Kent - I believe you are on to something. No matter what, whenever move pixels are packed into a give area, their size must be reduced. There is a trade off between higher resolution and noise. However. with the improvements in electronics, noise hopefully was reduced. Granted, applying the same improvements to the older larger pixels would result in even better noise reduction. But, there is a point at which one does not "see" the noise and the improvement in resolution at the expense of noise is worth it.
Remember, everything is a compromise. Let's hope that the choice made are optimal.
Posted by Ernie Atkins on August 26, 2007 at 4:03 PM
David B. said it well with his statement: "everything else equal ..." Sensor technology items he lists are improving such that today's smaller pixels outperform yesterday's larger pixels. It's true folks get caught up in pixel count. While important - overall camera features such as ability to shoot RAW, etc. can be just as important depending on the application.
The switch from CCD to CMOS was inevitable. A CMOS sensor can be produced at a greatly reduced cost and the improvements result in performance that rivals and surpasses CCD sensors. There will always be a place for CCDs (especially scientific apps) but CMOS is becoming the only sensor available in the commercial market.
Discussion
3 repliesEnough of the numbers. As a general rule, the bigger the pixel pitch (actual size of the pixel sensor) the lower the noise, and the better the high ISO/low light performance. So, are Canon & Nikon just playing games here? It looks like all they have done is pack a few more pixels onto their sensor by making them smaller. Isn't there a risk the image quality will actually be lower, especially in low light? One thing I can't figure in is Nikon's switch from CCD to CMOS. Not sure if one is better than another. The appearance is they are both trying to jam more but smaller pixels onto a sensor to impress the less sophisticated buyers. The processing did go up from 12 bit to 14 bit. Will that be enough to overcome the smaller pixel pitch? Maybe we'll have to wait until there are actual image samples.
Kent in SD
Now I don't know if this means that the new sensors will definitely be better. The jump from 8 to 10 MP is not very large, but if you're making prints it's that much less you have to enlarge for a given size print, which also helps with apparent quality.
Remember, everything is a compromise. Let's hope that the choice made are optimal.
The switch from CCD to CMOS was inevitable. A CMOS sensor can be produced at a greatly reduced cost and the improvements result in performance that rivals and surpasses CCD sensors. There will always be a place for CCDs (especially scientific apps) but CMOS is becoming the only sensor available in the commercial market.